Li-ion batteries are the predominant form of energy storage in personal electronic device applications. A typical Li-ion battery is composed of a positive electrode (cathode), a negative electrode (anode), an electrolyte, and other accessories. The simplest anode material, lithium metal, suffers from safety issues due to uneven or dendritic deposition during battery charging. Thus lithium metal anodes have become disfavored for many applications despite their high capacity and low electric potential, the latter providing a maximal potential difference across the cell. Current state-of-the-art anode material is graphite, an insertion-type anode, which only delivers a capacity of ˜370 mAh/g. In addition, the low electric potential for lithiation of graphite (˜0.1 V vs. Li/Li+) can lead to surface deposition, raising the same safety concerns at high current density operation that are present for lithium metal anodes. While numerous possible anode materials have been proposed as replacements for graphite, including examples such as Si and Li4Ti5O12, the discovery and development of additional anode materials having high capacity and useable lithiation potential for lithium-ion cells remains an important field.
Bulk TiS2 is the first electrode material to have been tested in a Li-ion cell, in the late 1970s. The lithiation of bulk TiS2 occurs at ˜2.1 V vs. Li/Li+, however, which indicates that bulk TiS2 can only serve as a cathode material.